Reland: [modules] Properly initialize declared variables.

src/interpreter/bytecode-generator.cc

 // Copyright 2015 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/interpreter/bytecode-generator.h"
 
 #include "src/ast/compile-time-value.h"
 #include "src/ast/scopes.h"
 #include "src/code-stubs.h"
 #include "src/compilation-info.h"
@@ skipping 914 matching lines @@
 
       Register name = register_allocator()->NewRegister();
 
       builder()
           ->LoadLiteral(variable->name())
           .StoreAccumulatorInRegister(name)
           .CallRuntime(Runtime::kDeclareEvalVar, name, 1);
       break;
     }
     case VariableLocation::MODULE:
-      // Nothing to do here.
+      if (variable->IsExport() && variable->binding_needs_init()) {
+        builder()->LoadTheHole();
+        VisitVariableAssignment(variable, Token::INIT,
+                                FeedbackVectorSlot::Invalid());
+      }
+      // Nothing to do for imports.
       break;
   }
 }
 
 void BytecodeGenerator::VisitFunctionDeclaration(FunctionDeclaration* decl) {
   Variable* variable = decl->proxy()->var();
   DCHECK(variable->mode() == LET || variable->mode() == VAR);
   switch (variable->location()) {
     case VariableLocation::UNALLOCATED: {
       FeedbackVectorSlot slot = decl->proxy()->VariableFeedbackSlot();
@@ skipping 19 matching lines @@
       Register name = register_allocator()->NextConsecutiveRegister();
       Register literal = register_allocator()->NextConsecutiveRegister();
       builder()->LoadLiteral(variable->name()).StoreAccumulatorInRegister(name);
 
       VisitForAccumulatorValue(decl->fun());
       builder()->StoreAccumulatorInRegister(literal).CallRuntime(
           Runtime::kDeclareEvalFunction, name, 2);
       break;
     }
     case VariableLocation::MODULE:
-      DCHECK(variable->mode() == LET);
+      DCHECK_EQ(variable->mode(), LET);
+      DCHECK(variable->IsExport());
       VisitForAccumulatorValue(decl->fun());
       VisitVariableAssignment(variable, Token::INIT,
                               FeedbackVectorSlot::Invalid());
       break;
   }
 }
 
 void BytecodeGenerator::VisitDeclarations(
     ZoneList<Declaration*>* declarations) {
   RegisterAllocationScope register_scope(this);
@@ skipping 1025 matching lines @@
         Register import_name = register_allocator()->NextConsecutiveRegister();
         Register module_request =
             register_allocator()->NextConsecutiveRegister();
         builder()
             ->LoadLiteral(it->second->import_name->string())
             .StoreAccumulatorInRegister(import_name)
             .LoadLiteral(Smi::FromInt(it->second->module_request))
             .StoreAccumulatorInRegister(module_request)
             .CallRuntime(Runtime::kLoadModuleImport, import_name, 2);
       }
+      BuildHoleCheckForVariableLoad(variable);
       break;
     }
   }
   execution_result()->SetResultInAccumulator();
 }
 
 void BytecodeGenerator::VisitVariableLoadForAccumulatorValue(
     Variable* variable, FeedbackVectorSlot slot, TypeofMode typeof_mode) {
   AccumulatorResultScope accumulator_result(this);
   VisitVariableLoad(variable, slot, typeof_mode);
@@ skipping 1432 matching lines @@
   return execution_context()->scope()->language_mode();
 }
 
 int BytecodeGenerator::feedback_index(FeedbackVectorSlot slot) const {
   return TypeFeedbackVector::GetIndex(slot);
 }
 
 }  // namespace interpreter
 }  // namespace internal
 }  // namespace v8